21st Divisional Artillery Instruction 23 June 1916
XV Corps 1
62 Inf. Bde. 5
63 : : 5
64 : : 5
Div. Art. 2
Div. Eng. 4
178 Tun Co. R.E. 1
50th Bde 1
F. Coy. R.E. 1
Reference 21 Div O.O. 55 dated 17/6/16.
On the night when the gas attack is ordered to proceed:-
1. Our front line trenches will be held as lightly as the circumstances permit.
2. All men in the front line trenches will wear their gas helmets.
3. All speaking and movement will be restricted to the necessary minimum, especially in the case of a cylinder bursting or gas coming into our trenches from any other cause. Shouting and running about must be avoided.
4. men wearing gas helmets must be careful not to show their heads over the parapets prior to the discharge of gas.
5. the TAMBOUR will be evacuated half an hour before discharge of gas, and will not be re-occupied until reported free from gas by an Officer of F Coy. R.E.
A. Hollingworth Capt.